[Jason67]

I have an NOS 428 fitted block that has brand new 50 year old cast pistons. Plans for the block are to run a 68 cast intake with RA II heads and a nitrided VooDoo 704 cam, NOS GM lifters, Harland Sharp 1.5 rockers, 428 nodular crank turned .010/.010. The piston valve reliefs and dish measure 14cc. I'm figuring compression will be 9.85:1. I'd like to use the cast pistons with pressed eagle H beams.

Question is, Do I need to / should I go with a forged piston?

Thank you

[mysticmissle]

Pistons are going to be hard to come by but with the components you are assembling I think you should go the extra mile and get the good pistons for the good rods
One of those pistons rattles
And breaks an ring land blah blah there could
Be damage to your $4000 set of heads

[PunchT37]

I agree with Mystic.


You might have to spend a little more, but these days, one can get pistons with the clearance built in. So, they are already "fitted".

[sdbob]

I would by the best quality.

[Half-Inch Stud]

Those NOS slugs will run better on ebay.

[Jason67]

Thank you for all the replies, I guess I knew the answer, just needed help making the right decision. Much appreciated, Jason.

[Sirrotica]

Speaking from actual experience, trying to run cast factory pistons in a race car only takes a small bit of detonation to destroy them. I used to have a wrecking yard as a sponsor, and when my good 428 engine was getting the machine work done, I tried to run a used, stock, 455 in my GP dirt car. I ruined it in one outing, by breaking the pistons from detonation. My 428 had forged pistons, and ran for 3 seasons with the stock bore, I still own the engine, it's just as I pulled it out of the race car, back in the late 70s.

Buy the lightest, forged pistons, you can afford, light weight just lessens the stress on the crank, and rods, and can help with reliability on the reciprocating assembly. Back in the day, all we had were the heavy TRW forged pistons, but now if I were to do it again I'd buy lightweight pistons because you'll probably have to have custom pistons made for a 428, might as well get as much weight out, as possible.

Believe it, or not, my pistons are hung on the cast connecting rods with aftermarket rod bolts. Not that I'd recommend using cast rods, but that's all I could afford at that time, and they have been run up to 6000 RPM, many many, times. They're not as delicate, as many would have you believe, but there are much better choices today.

I was in the process of building a 455 with fully ported RA IV heads with 455 SD rods, dished TRW pistons, but my daughter was born, and my job, got in the way. I still have the parts, I just never assembled the engine, nor finished building the new race car. It would have been, a 70 Judge clone, if I had finished it, black, with gold accents, just like my previous race cars were painted.

Good luck with the 428, sounds like it should run very well for you.....

[PAUL K]

Factory cast pistons are light years better than any aftermarket cast piston as far as strength goes. If it's a "fitted" block with GM pistons I would use those and save a bunch of money. If you need pistons, forged is the way to go but a third of the "off the shelf" forged choices have a lot of short comings.

[MarkS57]

I don't know how the group feels about DSS but Bulter shows a 14cc dished forged. I was considering these for my 428.

https://butlerperformance.com/i-3164...tegory:1459591

[tom s]

Got a true non race street car I would run the fitted pistons in a heart beat.Tom

[Skip Fix]

My first race car my 409 Impala started life as the 340 HP low perf 409 with cast pistons. Hammered on it hard for years 6000 rpm side steps. Ran 106-108 mph in the 1/4 in a 3860lb car. Cast pistons did not hold up to dropping an exhaust valve though! Never found the valve head. I'd bet for a mild motor you'd be fine.

[geeteeohguy]

In the early 80's I ran stock cast pistons in a 1969 360 HP 428 that came in my '65 GTO. It ended up breaking the lands out of 4 or 5 pistons due to detonation I never heard.

The engines I have rebuilt have all been with old-school forged pistons and they seem to last forever. I agree that old USA factory stuff is going to be head and shoulders above newly produced stuff of the same construction.

[25stevem]

If the OP is not planing on making over 400 Hp and reving over 5500 those stock pistons will be just fine.
As with any motor if your tune is off far enough to create heavy ping or detonation then something given enough time is going to go south on you. Be it pistons if there cast, or rod bearings if your running forged pistons.

You will need to run a aftermarket rod that will take a pressed pin which is no big deal.

Naturally a balance job will be needed.
It will be very important to reinstall the pistons in the hole they came out of since the piston where selected on the assembly line to match up best with a given size bore tolerance wise.

[Formulas]

if used the key to survival will nothing to far out of whack such as ignition timing, fuel ratios, cam degreeing, over heating, and a red line value..

i knocked ring lands out of 2 stock engines didnt do any secondary damage just smoked ALOT

Not sure you cam get that camshaft anyways

[PAUL K]

Generally speaking, forged or cast pistons don't bode well to valves dropping or heavy detonation. Cost is another advantage the cast pistons have over the forged pistons. If you plan on detonating them to death or dropping valves, you will be money ahead by using the cheapest cast pistons you can find.

[Half-Inch Stud]

Hmmm, Pontiac 350 slugs are bulletproof, while the 428-455 upper ring land are wine glass sensitive to detonation under load.

[Formulas]

Originally Posted by Half-Inch Stud

Hmmm, Pontiac 350 slugs are bulletproof, while the 428-455 upper ring land are wine glass sensitive to detonation under load.

Its much harder to get a 350 Pontiac into a high compression detonation zone due to available combustion chamber sizes as built from the factory or even swapping heads around 40 or so years later, nothing special about the pistons

my only ring land breakage experiences came from pushing the timing envelope on a stock 1968 gto and a stock 1970 400 Formula

4 pistons on the 68 and 3 on the 70 they ran real good until the smoke came out and really didnt run that bad right before tear down and ZERO cylinder wall damage

If i had the OPs 428 situation i would probably use 6x4 heads milled a bit and have fun

.

[PunchT37]

RA 2 heads and a Voodoo 704? All the more reason to go forged. IMHO.

[Sirrotica]

Originally Posted by Half-Inch Stud

Hmmm, Pontiac 350 slugs are bulletproof, while the 428-455 upper ring land are wine glass sensitive to detonation under load.

Not quite, I've broken factory 350 pistons, 389, 400, 428, and 455, pistons.

[25stevem]

RAII heads really good not make hardly any more power with factory cams up to the 068 then any other high comp D port head.
Even though they are round port exh style, they still have the stock D port type and size intake port.